Blade fastening



My 20, k1924.

C--GlLsoN BLADE FASTENING Filed May 314 x92] Patented May 2Q, 1924.

' UNITED s'rn'if'lasA PATENT OFFICE."

CHRISTIAN GILSON, OF HOMEVOOD, CPEN'NSYLV'ANIA, ASSIGNOR-.TO 'ESTINGI'IOUSEV ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OIF PENNSYLVANIA.

BLADE FASTENING.

Application filed May 31,

To all ywhom t may Concern:

Y Be it known that I, CHRISTIAN GiLsoN, a citizen of the United States, and a resident of Homewood, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Blade Fastenings,l of which the following is a specification.

vy invention relates to' fastening means for the blades of steam turbines and similar .structures and it has'for its object to provide apparatus ofthe character designated which shall permit the use of blades of uniform cross-section throughout; and which shall so securely fasten these blades that a greater force is required to pull them out than is required for the actual disruption of the blade. A further object of my invention is'to provide blade fastening means which shall be simple and inexpensive in construction and readily inserted during the assembly of'a turbine.

Referring to the accompanying drawing for a more detailed understanding of my invention, I show a side view of, a portion of a blading row in Figure 1, partially in section and partially in elevation; Figures 2 Vand 3 are views, partially in section and partially in elevation, taken transversely of the structure shown in Figure 1 and on the planes II-II and III-III, respectively;

Figure 4 is a top plan view of the Ymain or locking wedge or packing piece employed in my blade fastening means; Figure 5 isa top plan view o-f the lower or supplemental packing piece; Figure 6 is a top view, partially in section and partially in elevation, of a blade together with a main and a supplemental packing piece as assembled prior to driving; and Figure 7 is a similar view of the structure shown in Figure 6 after the v completion of the driving operation ;l Figure S isa top plan view of a special tool employed in driving home the packing pieces of the previous figures; and Figure 91s .a

side view, partially in'sectionand partiallyr in elevation of'thetool shown in Figure 8, being taken on the plane IX-IX.

In the mounting of blades in steam turbines and similar structures, itis essential that the mounting means shall securely hold the blade in position. not only'against the direct pull of centrifugal force ybut also 1921. serial No. 473,971.

'It has been proposed hitherto to mount Ablades by `upsetting the lower end of the root thereof and by hooking this upset portion under a packing piece engaging in an undercut slot or groove on the spindle. orv

cylinder of the turbine, as the case lmay be.

Blade fasteiiiiigs of this character have givenextremely good results in service'but experience has shown that the upsetting operation on individual blades is a somewhat expensive process, requiringcareful manipulation and workmanship for the best results. In accordance with the present invention, I provide blades'of uniform cross-section throughout, that is to say, they are cut directly from blade stock without anyV upsetting opera-tion and I mount these blades between main packing pieces engaging Vin an under-cut slot, the main packing pieces being similar to `those of the prior art. I further provide a straight slot in the bottom of the under-cut slot, the blades extending to the bot-tom thereof and I place supplemental packing ypieces in this lower .show a portion of lafou'ndation piece at 11 in Figures 1, 2 and 3, this vbeing either a portion of the cylinderk or aportion Yof the Y spindle of a steam turbine. An under-cut slot or groove 12l is provided'in thefpiece 121.

andvin the bottom thereof there is cut a further straight sided slotor groove 13of a width substantially equal to the blade width. These two grooves together constituterwhat may be termed a compound fastening groove or slot.

Blades 14, 14, 'of uniform cross-section throughout, are inserted in the compound slot., reaching to the bottom ofthe lower slot 13, and `main'packingpieces 15,15 are inserted therebetween, these packing pieces extending to the bottom of the under-cut slot 12 and being provided with wedgesliaped sides, as indicated at 16 iii Figures 3 and 4. rThe pieces 15 are roughly crescent shaped in plan view, as shown in Figure 4t, but having blunt ends and are designed to Afill the spaces between the adjacent blades that" of ablunt-ended crescent, similar to the plan view of themembers 15, except that flat spots 18 and 19 are provided 'on the 'concave and convex faces, respectively, for

a purpose to be hereinafter more fully described.

Referring now to Figure 6, it will be noted that a blade 14e has a main packing piece 15 fitting snugly thereagainst, and under-- neath the packing piece 15 is seen a supplemental packing piece 17, which does not lit snugly against the convex facel of the blade 1st because of the fiat portion 18, this being the condition of the blade assembly prior to driving the parts home.

, Figure 7 shows the position of the parts after they have been driven home and it will be' noted that the respective ends of the member 17 now coincide with the respective'ends of the member Y15, these two members being of identical contour except for the flat spots 18 and 19 on the member 17. `It will further bev noted that the flat portion 18`of the member 17 has been forced against and into the blade structure to such an extent as to ldeform the blade and cause a portion thereof to protrude, as indicated `inain packing 'piece 15.

Yat 2O. Y"This jrdefoimin, is clearly indicated at` the roots ofthe blades in Figure 1.

In lthe carrying out of my invention, it is advisable to employ avsuitable tool for driving home the packing pieces, and'V suchk a tool is illustrated in Figures 8 and 9, wherein a handle 21 carries a1 driving head 22 pro'- vided with a face'QS conforming in its shape to the backs ofthe main packing pieces 15S but alsoprovided'adjacent its lower edge with a driving tongue or lug 24, as clearly shown in Figure 9.

In the driving home ofthe lpacking pieces, they are first assembled, as shown in Figure 6, and the driving `tool is then so placed that the'tongue 2li bears against the flat face 19. Under these conditions, all the driving force .is exerted against the supplemental packing niece 17 until the blade is deformed to the desired extent, when the Vcurved driving face comes into Contact with the back of the By this means it isY at all times assured that the unflattene-d convex face of the supplemental packing piece 17 shall always be directly in line with theconvex face of the packing piece 15, all as is desirable for securing a'uniform and rigid spacing of the blade members.'

1t should further be noted that the shearing engagement of the blade between the each main packing piece so thatvsubse'quent to assembly7 the inspector may insert a wire therethrough and assure himself that all the supplemental packing pieces-have been in serted. Y Y

It will be obvious to those skilled in the -nsy art that my invention is susceptible of various modifications, as in causing the Vdeforming` port-ions 18 and 19 to take other shapes; such for example, as a hump at the point 18 and a hollow at the point 19, but lf do not consider such modifications as these to depart from the spirit of my invention. It is -extremely desirable, however, that all bladedeforming portions ofthe members 17 shal be located 'near the centra-l portion thereof and that VVtheends of the members 17 shall` conform in contour to the corresponding portions of the member 15, sothat'the blade edges shall not be distort d from their proper position. 1 Y

lVhile I have shown my invention in bur oneform, it will be obvious to those skilled i' in the art that it is not solimited but is susceptible: of various other changes and modifications withoutdeparting from the spirit thereof, and I desire, therefore, that only suoli limitations shall be placed thereupon as areimposed by the` prior art or as are specifically set forth in the appended claims. i 'i `What 1 claim is: f

V1. In a turbine blade assembly, locking packing means for a blade comprising an upper member and a 'lower member of equivalent blade-supportiiig cross-section in iior planes normal to the longitudinal axis of the blade bntwith their traces in said planes of'dissimilar conigurat-ion.v v

2. ln a vturbine, blade assembly,flocking means for a blade comprising anupper wedge'member abutting against the blade in Y a face conforming tothe normal blade face `and a lower member abutting against the blade in a face not conforming to the normal Vblade face. 'said lower member being` forced' against the blade to deform Ythe same.

3. In a turbine blade, assembly, locking means for a blade comprising an upper member abutting against the blade in a face conforming to the normal blade face and a lower member in general conforming to the blade shape but less concave in its concave face than the convex surface of the blade and less convex in its convex face than the concave face of the blade.` l j 4. ln a turbine blade'assembly, locking means for a blade comprising an upper member abutting against the blade in a face conforming to the normal'blade face and a lower member in general conforming to the blade shape but having a blade-engaging concave face differing in contour from the convex blade face and having a blade-engaging convex face similarly diering in contour from the concave blade face.

5.111 a turbine blade assembly, the combination with a foundation member provided with a compound groove formed of an upper groove with undercut sides and a lower groove in the bottom thereof having straight sides, said lower groove conforming to the blade width, ofa series of blades inserted in said compound groove and spaced apart by main packing pieces having wedging sides adapted to engage the walls of said undercut groove, and supplemental packing pieces between said blades and lifing in said lower groove, said supplemental pieces being so shaped as t'o deform'said blades when driven home.

6. In a turbine blade assembly, the combination with a foundation member provide-d with a compound groove formed of an upper groove with undercut sides and a lower groove in the bottom thereof having straight sides, said lower groove conforming to the blade width, of a series of blades inserted in said compound groove and spaced apart by main packing pieces having wedging sides adapted to engage the walls of said undercut groove, and supplemental packing pieces between said blades and lying in said lower groove, said supplemental pieces having con- Vex and concave faces for engaging the concave and convex faces, respectively, ofthe immediately adjacent blades but the respective degrees of convexity and concavity ofthe packingpiece faces not conforming accurately to the corresponding degrees of concavity and convexity of the coating blade faces, whereby, when said supplemental packing pieces are driven home, said blades are slightly deformed and thereby locked beneath said main packing pieces.A Y

7. ln a turbine blade/assembly, the combination with a foundation member provided with a compound groove formed of an upper groove with undercut sides and a lower groove in the bottom thereof having straight sides, said lower groove conforming to the blade width, of a,fseries of -blades inserted in said compound groove and spaced apart by main packing pieces having wedging sides adaptedto engage the walls of said undercut groove, and supplemental packing 'pieces betweensaid blades and lying in said lower groove, said supplemental pieces having'convex and concave faces for engaging the concave and convex faces, respectively, ofthe immediately adjacent blades, the respective bladeengaging faces of said supplemental l'packing pieces being provided with; Hat `portions yadjacent the centers thereof, whereby, when said supplemental pack-- ing pieces are driven home, said blades are slightly deformed and caused to be locked beneath the respective main packing pieces.

8f A packing piece for use in a turbine blade assembly having a general crescent shape, a convex edge conforming, in general, io the concaveface ofthe blade to be mounted and the concave edge conforming, in general, to the convex faceof the blade to be .mounted, said convex "edge, however, being slightlycut away over a portion. of its length, from the-true correspondingblade shape and said concave edge correspondingly protruding beyond the true corresponding blade shape over a portion of vits length.

A 9.l Apacking piece for use in a turbine blade assembly having a'general crescent shape, the convex edge conforming, in general, to the concave face ofthe blade to be mounted and the concave edge conforming, in .general to thev convex face of the blade to -be mgounted, said convex edge, however. having a flat portion adjacent its center and said concave edge having a corresponding flat portionadjacent its center.

10. A compound packing unit for use in a turbine blade assembly comprising a main upper packing' piece of a general crescent shape having wedging sides for engagement ina locking groove and a supplemental lower packing piece also having a general crescent shape and conforming' to the contour 'of said main packingfpiece throughout its major portion lbut departing from said contour in a minor portion.

11. A compound packing unit for use in a turbine blade'assembly comprising a main "upper packing piece of a genera-l crescent shape having wedging sidesfor engagement inj a locking groove and 'a supplemental lower packing piece also having a :general crescent shape and .conforming to the con- .tcur of said main ypacking piece adjacent its limbs but departing from the 4contour of said main packing piece adjacent its center.

l2. A compound vpacking unit for use` in a turbine blade assembly comprising a `main upper packing piece ofa'general crescent shape having `wedging sides for engagement in a4 locking groove and a supplemental'lower packing piece also having a general crescent shape and conforming to thecontour of said main packing pieceV but having less conc-avity -in the central portion ofits concave face and less'convexlty in the central Cil g l p 1,494,731

portion of its convex face than the lcorrespondingportion of the .respective faces of said main packing piece. f Y

13.` rlhe method of vassembling turbine blades ina blade mounting comprising niain packing pieces conforming accurately to the blade shapes and engaging in an undercut slot and further comprisingfsupplemental packing pieces under saidv main 'Jacking pieces not conforming accurately to the'blade shapes which comprise inserting said elements-iii a. suitable mounting slot and forcing said supplemental packing pieces into such predetermined relation to r said main packing pieces that the blades are deformed thereby and caused to engage under the immediately adjacent main packing pieces. Y

1.4. The method" of assembling turbine blades in a blade mounting comprising main packing pieces conforming accurately tothe blade shapes and engaging'in an undercut slot and further comprising supplemental packing pieces under saidY main packing pieces, and conforming, iii part, to the configuration of said mainpacking pieces but not conforming accurately to the blade sbape,' which comprises inserting said Yelements in a suitable mounting slot and forcing said Vsupplemental packing'pieces into alignment Ywith the similarly shaped p0rtions of the main p-ackingpiece, whereby the blade is deformed and thereby caused to positively engage beneath an j adjacent main packing piece. Y I

A15. The method of assembling turbine blades of crescent-shaped cross-section in a blade mounting comprising main packing pieces of crescent shape conforming accurately to the respective blade' faces and engaging' in an undercut holding slot and further comprising supplemental crescentshaped packing pieces underlying said main packing pieces and having limbs conforming accurately tothe shape of the limbs of sai-d main packing pieces but having less V concavity at the center of the concave edge thereof, and less convexity at the center' o f the convex edge thereof than theA corresponding portions of the main packing pieces which comprises assembling said elements in lsaid slot and driving home said iimcking pieces with a. tool' having straight f faces for engagement with the respective limb portions of said packing pieces, Wherehv tlievlimbs of eachsupplement-al packing piece are brought into alinement with the corresponding limb of t-he associated main packing piece', iespectively,and said center portions of thesupplemental packing pieces are caused `to deform the respective blades te cause engagement thereof under the associatedmain packing pieces'.

V16. The method of assembling turbine blade-s of. crescent-'shaped cross-section in by said straight too-l faces.

a blade mounting comprising main packing pieces of crescent shape conforming accurately to the respective blade faces and e'n- Y gaging in an undercut holding .slot and further comprising shaped packing pieces underlying said main packing pieces and having limbs conforming accurately to the shapeof the limbs of said main packing pieces-but having less concavity at the center' of the concave edge thereof and less convexity at the center of Vthe convex edge thereof than the corre-4l sponding portions of the main packing pieces which comprise assembling said ele-V S() ments in said slot and driving home said packing pieces with a tool having straight `faces for engagement with the respective limb portions of said packing pieces, and having anl extension for engagement with the center portion ofthe supplemental'packing piece, whereby said supplemental packing pieces are not caused to deform the respective blades for engagementunder the associated main packing piece and whereby the limb portions lof, each supplemental packing piece are subsequently brought into alinement with the corresponding limb portion of the associated main packing piece 17. In a blade-1 mountingV structure for turbines, the combination with a foundation Y member having an undercut slot of. wedgeshaped packing' pieces seated therein and engaging the blade roots and means beneath said packing pieces for deforming the blade roots in a circumferential direction,

thereby resulting in outward movement of -said wedge-shaped packing pieces into firm supplemental 'Y crescentpacking pieces beneath said main packing ieces said su lemental ackinfrz ieces so 7 VC Y i deformingsaid blade roots asto causean outward expansion forcing Ysaid Wedgeshaped packing pieces into iirm'engagement With the walls of sa idundercut slot.- Y

19. In a tui-bine, thecombination of a foundation memberhaving an undercut groove with aV countersunk Vslot therein,V a plurality of blades in t-he groove and slot, packing pieces in the groove, and-'packing pieces in the slot which, when driven home,

result in deformation of the blade roots tending to forcethe first packing pieces up- I Wardly into firm engagement With the sides of the undercut groove and tending to force the secondv packingV pieces firmly into contact with the bottom ofthe slot. i

20. In aV turbine, the combination ofr a downward lv foundation member having an undercut groove therein, a plurality of blades in the groove, wedge-shaped packing pieces in the groove and` arranged between the blades, and other packing pieces arranged between the blades and below the first packing pieces for securing a circumferential deformation of the lower portions of the blade `roots when the blading and packing pieces are assembled.

21. In arturbine, the combination of a foundation member having an undercut groove with a countersunk slot therein, a plurality of blades in the groove and slot, wedge-shaped packing pieces fitting the groove and having blade-engaging surfaces, and packing pieces in the slot for securing a circumferential deformation o-f the lower portions of the blade roo-ts when the blading and packing pieces are assembled.

22. In a turbine, `the combination of a member having a groove, a plurality of blades in the groove, upper packing pieces in the groove having surfaces which are conjugate to the'blades, and other packing pieces below the first packing pieces which vhave blade engaging surfaces differing in outline from the blade-engaging surfaces of the first packing pieces.

23. In a turbine, the combination of a member having an undercut groove, a plurality of blades in the groove, wedge-shaped packing pieces in the groove and between the-blades and having surfaces which are conjugate to the blades, and other packing pieces below the Vfirst packing pieces and having blade-engaging` surfaces which are dissimilar in outline to the blade-engaging surfaces of the first packing pieces.

In testimony whereof, I have hereunto subscribed my name this 24th day of May, 1921.

CHRISTIAN GILSON. g 

